Inside caliper



A. A. BALK Feb. 7, 1950 INSIDE CALIPER Filed Jan. 2o, 1947 nigh..

INVENTOR. BYALes-:RT A. @ALK )JLDLL W o NEX ATT Patented Feb. 7, 1950 Irv...

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UNITED STATES PATENT OFFICE INSIDE CALIPERv AibertA. Balk, cleveland, ohio.

Application January 20, 1947, Serial No. v723,137

1 Claim.

any one button will serve a distinctive portion of the entire eld of measurement covered by the calipers. The structure provides for use of the calipers over the smallest range without utilizing any button.

The annexed drawing and the following description set forthin detail certain means illustrating the improvements in inside calipers, such means presenting, however, only one of the vari-l ous forms in which the principle of the invention may be embodied.

In said annexed drawing:

Figure 1 is a partial side elevation and partial axial section of the improved inside calipers with the sliding plunger in locked position, the view showing one of the selective extension buttons incorporated with the caliper main assembly;

Figure 2 is a section, upon an enlarged scale. taken in the planes indicated by the lines 2 2, Figure 1;

Figure 3 is an exploded view of the structure shown in Figure 1 except that it does not include the extension button shown in Figure 1; and

Figure 4 is an elevation of a plurality of buttons of different lengths.

Referring to the annexed drawing in which the same parts are indicated by the same respective numbers in the several views, a, longitudinally recessed caliper body I is formed with a ball head 2 whose axis is normal to the body axis, the head 2 having a bore 3 within which one end of a bushing 4 is secured with a press t, the end face of the bushing 4 lying flush with an end face of the ball head 2. The enclosed end 6 of the bushing 4 is open and the portion of the bushing 4 extended from the ball head 2 is of reduced section for the greater part of its length and has a closed end 'I formed with a contact face 8. The outwardly extended part of the bushing portion of large section is externally threaded.

A plunger 9 telescopes in bushing 4 and is formed with an elongated axial recess 91 adapted to receive a coiled compression spring I2 which at one end bears upon the inside face of the closed end 1 'of the bushing 4 and at its other end bears upon the end wall of the recess 91. The outer end I0 of the plunger 9r is closed and has an exterior contact face II. A groove I3 is formed in one side of the plunger 9 and holes Il and 41 formed in the 'body I and the bushing 4, and which are aligned when the calipers are assembled, have axes which intersect the groove I3.

A tubular handle I6 is externally threaded at e one end I1 for engagement with an outer internally threaded end I5 of the body I and the opposite end I8 of the handle I6 is interiorly threaded for engagement with an exteriorly threaded end 2| of a tubular lock spindle I9.

- The threaded end 2l of the lock spindle I9 is formed with an axial recess 22 against the base of which is seated one end of a lock pin 23 which intersects thehandle I6 and body I and whose other end is adapted to pass through the aligned holes Il and 41 and engage the groove I3 to hold the plunger 9 in the bushing 4 against the compression of the spring I2. The other end 20 of the lock spindle I9 is interiorly threaded for engagement with an externally threaded end stem 25 of an extension handle 24.

The device thus far described will serve as calipers for measuring inside diameters over a field of from about 1" to 11A", for instance. Now, for the next field of operations; possibly from 1% to 11/2", an extension button is utilized; and, forstill larger fields of operations, progressively longer extension buttons. Four of the buttons of different lengths are shown in Figure 4, viz., 26, 21, 28, and 29. Each of these buttons has a closed end with a contact face, such as contact face 30 on button 2B, for use in conjunction with the contact face I I of plunger 9 for the measuring or gauging operation.

The bushing 4 and the extension buttons are formed to permit quick assembly of a button, or the replacement of one button by another button, by the provision of a cylindrical recess 32 in the button whose wall serves as a bearing surface for the side wall of the closed end of the bushing 4, the extension button being attached by means of an open intericrly threaded inner end 3I which engages the externally threaded part 5 of the bushing 4.

Thus, by the bushing structure shown and described, together with a plurality of selective cooperating different length extension buttons, the eld of possi-ble measurement by any one caliper assembly, which assembly is complete for the entire rleld except for the particular extension button selected. is greatly increased.

The use and functioning of calipers of the character described is Well-known and consists briefly in placing the ball end of the calipers in the hole to be measured, with the plunger 5l in its innermost locked position, then backing off the lock spindle I9 to permit the contact faces Il and 8 of the plunger 9 and the bushing 4, or the contact faces ll and 30 of the plunger 9 and the particular extension. button utilized, to engage the wall of the hole being measured, and then the calipers set at that measurement by again tightening the lock spindle I9, after which the calipers are withdrawn from the hole and the measurement read by a micrometer or other suitable means.

What I claim is:

Inside calipers, comprising a tubularl bodyhaving a ball portion formed with a bore, a bhing r secured in the bore and having an end face disposed. substantially iiush with` an end face of. the body ball portiorrsaid bushing having a closed extended opposite endportion formed with a contact. face, a longitudinali-y-recessed plunger tele scopically tti-ng the bushing ami-extended from the end oi the bore opposite the extended. end of the bushing, the plunger havingA a closed end formed with a contact face, a compression spring mounted in the recess of the plunger and in the bushing and bearing on the latter at oneencl and on the inside face of the Closed-end of the plunger at the other end, the plunger being formed with. an exterior side groove, coaxial holes formed. in the ball and bushing whose. axes intersect the*A groove, ay tubular handle secured tothe body,y a

lock pin: loosely disposedwithin thee bod-yI and handle, movable longitudinally thereof, aligned; withthe holes,` andY adapted toengage the groove with one end to holdv ther plunger locked-against the compression of the spring, a lock spindle mounted on and movable longitudinally of the handle and engaging the lock pin, said bushing being formed with an end portion of comparatively large diameter secured in the bore and slightly extended from the latter, together with an opposite end portion of comparatively small diameter, the slightly extended large portion of the bus-hing being exteriorly threaded, and an open-ended button of uniform diameter, internally threaded at its open end, engaging the bushing thread, having a bearing surface for the gressively greater length can be selectively attached to the bushing for measurement of inside diameters over diierent ranges of measurement.

. ALBERT A. BALKL REFERENCES CITED The following references are of record in theille o `this patent:

UNITED STATES PATENTS Number Name Date 1,559,801 Steinle e Nov. 3, 1925 2,223,182 Muller Nov. 26, 1940 2,326,410 Swinney Aug. 10, 1943 FOREIGN PATENTS Number Country Date 68,847 Switzerland July l1, 1914 V OTHER REFERENCES Publ.: Popular Science Magazine, April 1944, p`., 173. 

